Rias Gremory is the main female protagonist of High School DxD. She is the next heiress of the Gremory Clan after her older brother, Sirzechs, took the title of Lucifer. She is the only daughter and youngest child of Zeoticus and Venelana Gremory, the aunt of Millicas Gremory, and the cousin of Sairaorg and Magdaran Bael. She is known as the Crimson-Haired Ruin Princess. She is a first-year college student at Kuoh Academy, the former President of the Occult Research Club, and the school's number-one beauty, as well as one of Kuoh Academy's Two Great Ladies alongside Akeno Himejima. She is also one of Issei's fiancees.
Rias is a beautiful young woman with white skin, blue eyes (blue-green in the anime, season 1-3) inherited from her father, Zeoticus, and a buxom figure. Her body measurements are [B99-W58-H90 cm] [B39-W23-H35 in]. Her body weight is [58 kg] [128 lbs]. Her most distinctive feature is her long, beautiful crimson hair which she also inherited from her father, that reaches down to her thighs with a single hair strand (known in Japan as ahoge) sticking out from the top. Her hair also has loose bangs covering her forehead and side bangs framing her face. Rias' height is 172 cm. (5 feet 8 inches), making her one of the tallest female characters of the series.
Although Rias has worn various types of clothing throughout the series, her most commonly worn outfit is the Kuoh Academy girls' school uniform, which consists of a white long-sleeved, button-down shirt (short sleeves for spring/summer), with a black ribbon on her shirt collar worn under a black shoulder cape and a matching button-down corset, a magenta skirt with white accents, and brown dress shoes over white crew-length socks. Rias also tends to wear seductive lingerie and thongs, especially when she has a desire to sleep with Issei.
On some rare occasions, Rias wears glasses when she's deep in thought, as she feels they make her mind work better despite having perfect eyesight.
Rias is a very kind and compassionate optimist, especially to her servants and people close to her. She gets angry and violent whenever people insult her or her peerage, showing a fiery side to her. This also plays into the fact that she dislikes cruelty towards people, as shown with her disgust over Marius Tepes, who abused his own sister for his own benefit, and how she killed the Fallen Angels, such as Mittelt, Dohnaseek, Kalawarner, and Raynare for their cruel treatment of Issei. She thinks of Issei as a special person and always gets jealous when girls are around him, becoming a totally different person when she sees him and other girls together, or when it comes to training. Despite her mature stature like a woman, Rias tends to act her true age and become frustrated whenever girls flirt with Issei.
She is proud of her family's name, but she does not like being seen as Rias of the Gremory Family. The reason for her living in the human world (as revealed in Volume 2 of the novels) is because there, everyone sees her as Rias, not as a Devil or as the Crimson-Haired Ruin Princess. Despite being seductive like Akeno, both of the girls are still innocent to love, as both of them become their age whenever around Issei or on a date with him.
She enjoys teasing Issei and Asia (from Volume 3 of the novels onward), but at the same time makes it clear (to Asia or any girl) that Issei is hers, and she does not want to share him at all (It is revealed in Volume 3 of the novels that the Gremory Family and their servants are beings with extraordinary affection among the Devils, so Rias is no exception). She has no problem with showing Issei her breasts or sleeping naked with him (which she always does according to her and she claims she can't sleep without being nude or without Issei).
After becoming Issei's girlfriend, Rias begins to show more confidence in her relationship with Issei and is no longer jealous or angry when Issei is with other girls like she previously was, even accepting Issei's dream of having a harem and letting the girls have dates with him. However, Rias still shows some signs of jealousy such as when Issei doesn't spend enough time with her, but still believes in him and loves him. Like Akeno, Rias shows a sign of dependence toward Issei (possibly lesser than the former) as Rias will lose her will to fight and lead.
She holds her older brother, Sirzechs, in high regard (despite her older brother's antics of being a siscon) because she deeply cares for him. When she was a child, she was entirely dependent on him and held him in admiration, while also feeling inferior to him at the same time.
Rias is the daughter and second child of the Gremory Family. She became the heir after her brother, Sirzechs, became the Satan Lucifer, losing his right as heir to the house. After being announced as the heiress of the Gremory Clan, Rias was eventually placed into engagement with Riser Phenex. When she was a child, she was attacked by a camel for making fun of it, which caused her to have a strong fear of camels ever since. Just seeing imagery of a camel is enough to trigger her fear, as shown when she gets frightened seeing her clan's mascot, which is a camel.
Prior to the series, Rias has reincarnated Akeno Himejima, Koneko Toujou, Yuuto Kiba, and Gasper Vladi as members of her peerage. Rias met Akeno, her Queen, first servant, and best friend, in Japan, saving Akeno from being killed by her fellow Himejima Clan members after Akeno accidentally entered Heinrich Cornelius Agrippa's territory. She then met Koneko, her second servant, after her brother rescued Koneko from being executed, leaving Koneko under Rias' care. She later reincarnated both Yuuto and Gasper, the former who died after being a part of the "Holy Sword Project" and the latter killed by Vampire hunters.
She entered Kuoh Academy two years before the series along with Akeno, Sona, and Tsubaki, reviving the abolished Occult Research Club which is used as a base for her servants and became its president. Rias and Akeno went to the Kyoto trip during their second year, Rias enjoyed every moment of it, however, they didn't plan a proper scheduled and therefore there were places that she wasn't able to visit like the Nijou-jou, Rias was so upset that she stomped her feet at the railway station. Also during their second year, Rias and her club organized a haunted house for the school festival, she even used real ghosts as she requested friendly Youkai looking for jobs to plan the decorations. This, however, got them in a lot of trouble with Sona who scolded them for using the real thing.
Powers & Abilities
Demonic Power: Rias has exceptional demonic power even for a High-Class Devil. Azazel has noted that even without training, she has the potential to become a Devil of the highest class relying solely on natural talent alone. Upon utilizing her demonic power of destruction, the surroundings will gradually shake to where her abilities are comparable to an Ultimate-Class Devil. In Volume 23, Rias completely overwhelmed an ultimate-class Devil, who was wounded by Crom Cruach’s initial blow state. When combined with her Forbidden Invade Balor Princess form, Rias is able to keep up with Fenrir in eighty percent of his original form. In True Volume 3, she can use her demonic power to change the color of her hair from crimson to blonde.
- Power of Destruction (滅びの力, Horobi no Chikara): A unique form of demonic power that allows her to release energies that can disintegrate matter, both living and inanimate, with relative ease. She is further able to control the shape and power of the technique such as creating multiple softball-sized bullets to lessen the destructive force yet increase the range of her attack. In Volume 5, Rias control further improves by compression of her power of destruction into countless number bullets in mid-air. Its stated those without enough power would vanish from just one bullet.
- Extinguished Star (消滅の魔星, Demonic Star of Extinction): Rias' ultimate one-hit kill technique made due to the change in her demonic power due to the influence of Issei's power. She manipulates her Power of Destruction into a compression of an unimaginable amount of demonic power; takes on the form of an enormous sphere with a mixture of crimson and black aura radiating from it that move toward her enemies at slow speeds. The Extinguished Star has a strong magnetic force, which pulls enemies towards it and is disintegrated similar to a black hole. Its destructive power has been stated to surpass the speed of the retiring system in the Rating Game.
Expert Magician: Rias is also shown to be proficient in using magic such as the ritual to drain the dragon aura from Issei's left hand to let it appear human again, teleportation magic, healing spells with the most fatal being restored after making skin to skin contact, defensive magic to protect herself and her servants from powerful attacks, and create several layers of defensive barriers to protect from the explosive aftershock of Katerea self-destruct spell. Rias can also use magic communication circles.
- Memory Alteration: Rias has shown that she has skills in memory alteration using it on Issei's Parents.
Enhanced Durability: Rias has shown great tolerance to damage and pain, she was going continuing to fight Regulus and remain in the rating game despite the intense blood loss.
Oppai Beam: Rias has gained the ability to project a red light from her breasts, which recharges Issei's energy. Each use of this power causes her breasts to temporarily shrink in size, which makes Issei cry even though it's sometimes necessary. Her breast size will restore itself after a few days of rest.
Expert Tactician: Though outsmarted several times throughout the series, Rias has proven herself to be an excellent tactician and has saved her team along with others many times due to her profound intellect and her ability to handle unexpected difficulties calmly.
Stealth Expert: Rias has learned how to mask her presence to allow to remain undetected, as a way to sneak behind and surprise Issei without being noticed.
Flight: Being a Devil, Rias can fly using her wings.
Crimson Extinct Dragonar (深紅の滅殺龍姫, Death Scarlet Destroyer Dragon Princess): A combination technique between Rias and Issei, where he uses his Red Wyverns and they sync both of their auras and the Wyverns attach themselves to Rias to create her own female version of Issei’s Scale Mail. The armor acts just like Issei's, boosting Rias's abilities and giving her the ability to utilize Boost, Transfer, and Penetrate until she reaches her limit.
Forbidden Invade Balor the Princess (禁夜と真闇の滅殺獣姫, Beast Ruin Princess of the Forbidden Night and True Darknes): A combination technique between Rias and Gasper, where he melts into his shadow and fuses with hers covering her in darkness. This resulted in a form of Rias, which appears as a dark beast in the shape of a human enveloped in a deep red aura of destruction and also a third eye with a deep red pupil and gain ten wings. This was inspired from Sairaorg's balance breaker supplemented by her Crimson Extinct Dragongar. Rias is able to use her third eye to freeze opponents in time and travel through shadows; her own power of destruction is also greatly enhanced with the infusion of power of darkness, as well as stop her own attacks and control them such as changing their trajectory. This form, while still incomplete, exceeds Satan-class power, and is able to casually destroy an area with a radius of a few hundred meters filled with skyscrapers.
Unnamed Red Sword: A crimson sword able to be used by a devil, which Rias had received from Heaven as a blessing after her engagement to Issei. She plans to pass it on to their future children.
- (To Issei upon death) "So you were the one who called me." (Volume 1, Life 0)
- (Introducing herself to Issei) "My name is Rias Gremory. I am a Devil. And I am your Master. Nice to meet you, Hyoudou Issei-kun. Can I call you Ise?" (Volume 1, Life 1)
- "There's one last thing you should never forget, Ise. Even a [Pawn] can take down the [King]. This is basic in chess. This truth also applies to the Devils' chess pieces. You can become stronger." (Volume 1, Life 4)
- (To Issei) "Geez... You're an honest kid with perverted thoughts too. Ufufu~♥" (Manga, Chapter 22)
- "Now my adorable servants! Let's blow away the enemy before us as the Gremory group!" (Volume 12, Life -2)
- "Insulting my servants warrants death!" (Season 2 New)
- "If you can get stronger and feel comfort by touching my breast, then I don’t mind being a Switch-Princess. The Switch-Princess that only belongs to you. If I can become the source of your power, then that will fulfill my wish. –My adorable Ise." (Volume 7, Life-3)
- "You finally called me by my name……… I have waited for this the whole time. I really did…… But I didn’t have the courage to tell you…… So I thought that it would never happen……… But when I heard your feelings that time……… I was so happy……… I was so happy that I was about to cry during the match………" (Volume 10, New Life)
- "A world without him! I don't care about the World without Ise! ……To me, he was….. that person was….. He was more important than anyone else. For me to live without him……" (Volume 12, Life -3)
- The reason why Rias has large breasts even at a young age is because of the blood of the Bael Clan.
- Rias was decided not to have large breasts originally, as Ishibumi said he intended Rias' sizes to be only a bit larger than the common girls in Japan would have. However, he inspected Miyama's illustration of her with big breasts, fell in love with it, and decided to give her large breasts.
- Rias' birthday is April 9th, according to official material.
- According to a questionnaire, her erogenous zone is located on her neck.
- In one of her original early concepts, Rias' design bore a striking resemblance to Tamaki Kousaka from To Heart 2.
- In one of the short stories, it is revealed that Rias is a big "Japanophile", having a huge collection of objects and artifacts back in her room in the Underworld.
- It is also the reason as to why she came to visit Japan in the first place.
- Rias mentioned that she wants a Japanese style wedding when she gets married and wants it in the Human world; possibly due to her being a Japanophile.
- Rias wants to have her wedding take place in Kyoto.
- Rias' name is derived from the Pokémon Garchomp ((Japanese: ガブリアス Gaburias). 
- The reason for this is because Ishibumi decided she must have a foreign name from the beginning.
- Rias is known as one of the "Rookies Four" along with Sairaorg, Sona, and Seekvaira.
- The other name for them is "The Four Novice Kings".
- Rias is the character that killed the most named characters in the series for a total of five characters (Raynare, Dohnaseek, Kalawarner, Mittelt, and Viser).
- Rias has a fear of camels; this occurs when she got hurt by wild camels after she sneaked out to go to the farm when she was still young.
- The Crimson Extinct Dragonar was inspired by the Extremis Iron Man Armor
- Originally, Rias wasn't even planned to be in the series.
- Ishibumi describes Rias as being the King, the mother, and the big sister of her peerage all at once.
- Rias's nickname Crimson-Haired Ruin Princess was taken from her mother's nickname Flaxen-haired Ruin Princess.
- Rias could play the piano when she was a child but it is unknown if she still can.
- Rias makes review videos of her “Switch Princess goods” and uploads them to DeviTube, with the accessories she wears in them secretly becoming popular as a compelling fashion choice.
- Rias is the first female character to be placed into an engagement, the second being Kiyome, and third being Rossweisse.
- Rias has a driving license.
- She owns multiple cars such as a red saloon and a red convertible being two of them.
- Rias had a dream of going on a drive date with Issei which finally came true.